Severus Snape had been working on his notes about Wolfsbane, nose deep into them, when he heard the knock, he pushed the parchment away with a groan and flicked his wand, so that the door creaked open with a rasp that did sound as if it came from hell when he resounded in the dungeons' wall.
"It is a pleasure to see you, Potter." he hissed slowly, his voice dragging in a tone of bored sarcasm.